<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    function array(arr) {
      let str = 0
      let left = arr[0]
      let right = arr[0]
      for (let j = 1; j < arr.length; j++) {
        right = Math.max(right, arr[j])
        if (arr[j] > left) {
          str = j
          left = right
        }

      }
      return str

    }
    console.log(array([5, 0, 3, 8, 6]))
  </script>
</body>

</html>